1. Field of the Invention
The present invention relates to an IC chip mounting method for mounting two or more IC chips on a base.
2. Description of the Related Art
In recent years, various types of RFID tags have been proposed which exchange information with an external apparatus typified by a reader writer in a noncontact manner through electric waves. As one type of the RFID tags, there has been proposed a structure in which antenna patterns for radio communication and IC chips are mounted on a base sheet formed out of plastic or paper. For this type of RFID tags, there have been created usage patterns such as article identification by attaching the tag onto an article or the like and exchanging information about the article with the external apparatus.
FIG. 1 is an elevational view (A) and a sectional side elevation view (B) illustrating an example of a RFID tag.
RFID tag 1 illustrated in FIG. 1 is constituted of an antenna 12 fitted onto a base 13 formed out of a sheet-like PET film or the like, an IC chip 11 connected to the antenna 12 through a bump 16 and a cover sheet 14 bonded to the base 13 using adhesives 15 with the antenna 12 and an IC chip 11 covered.
An IC chip 11 constituting the RFID tag 1 can make radio communications with an external apparatus through the antenna 12 for information exchange.
For the RFID tag, a wide range of usage patterns including the usage pattern described above have been created, however, use of the RFID tags in various types of usage patterns has a severe problem on manufacturing cost thereof, accordingly various efforts have been made for reduction in the manufacturing cost.
FIG. 2 is a view illustrating a general IC chip mounting method, one of conventional methods for RFID tags.
As illustrated in part (A) of FIG. 2, the whole surface of a back side (the other face of a wafer having a mounting surface to be attached to a base sheet) of a wafer 10 built out of various types of IC chips is mounted with a tape 30 and further divided into IC chips 11 leaving the tape 30 by dicing.
As illustrated in part (B) of FIG. 2, one of a large amount of IC chips 11 on the wafer 10 is pulled and taken off from the tape 30 and held up using a picking jig 32.
As illustrated in part (C) of FIG. 2, the picking jig 32 with the IC chip 11 sucked is turned upside down.
As illustrated in part (D) of FIG. 2, the IC chip 11 is transferred onto a bonding head 33.
Furthermore, as illustrated in part (E) of FIG. 2, the bonding head 33 carries the IC chip 11 onto the base 13, places the chip on a proper position connected to the antenna 12 formed on the base 13 and, as illustrated in part (F) of FIG. 2, solders the IC chip 11 onto the base 13 by pressurizing and heating. When the bonding head 33 is then moved from the IC chip 11, IC chip 11 mounting is completed as illustrated in part (G) of FIG. 2.
Respective processes illustrated in parts (B) to (G) of FIG. 2 are sequentially repeated for a large amount of IC chips 11 on the wafer 10.
However, this mounting method requires to sequentially perform, for each IC chip, a complicated process that the IC chips 11 on the wafer 10 are picked up one by one, inverted, delivered to another jig (bonding head) and mounted at the bonding head, thus impairing productivity and increasing manufacturing cost.
As one method for reducing the manufacturing cost, Japanese Patent Laid-Open No. 2003-242472 has proposed that recessed portions for embedding IC chips are formed at intervals on a traveling web material (base), the IC chips are fitted into the recessed portions and antenna patterns are printed by means of an ink jet method so as to be connected with the IC chips fitted into the recessed portions.
However, the method proposed by Japanese Patent Laid-Open No. 2003-242472 includes filling a tank with liquid to float the IC chips in the liquid and traveling the web material (base) through the tank inside to fit the IC chips into the recessed portions on the web material (base) in mounting the IC chips into the recessed portions on the web material (base). The conventional method has a problem of low process reliability of fitting the IC chips into the recessed portions because the IC chips are not always fitted exactly into the recessed portions in a proper direction and the recesses having no IC chips therein may pass through the tank inside. Even if the IC chips are properly fitted into the recessed portion, the antenna pattern needs to be positioned with high accuracy relative to the IC chips fitted into the recessed portions. Moreover, if a negligible error occurs at a position where the IC chips are fitted into the recessed portions, a printing position of the antenna pattern needs to be changed according to the error, which may not yield high productivity.